Not applicable.
Not applicable.
Not applicable.
This invention relates to an internal combustion engine, to a method of handling compressed gas in an internal combustion engine, and to a blow-off valve apparatus and a system for use in an internal combustion engine.
Superchargers are utilized in internal combustion engines to increase volumetric efficiency of the engines and thereby to enhance the performance of the engines. When the throttle of such an engine closes during operation, certain detrimental effects can result. These include a build-up of pressure downstream of the throttle with a resultant undesirable increase in heat, a rapid deceleration of the supercharger compressor with a resultant increase in potentially damaging or wearing forces on the compressor, excessive and unpleasant noise effects, and an increase in the ratio of fuel in the fuel/air mixture supplied to the engine which results in the engine running rich.
In an attempt to overcome at least some of these disadvantages, a blow-off valve (also known as a by-pass valve or anti-surge valve) may be provided downstream of the supercharger compressor outlet. Such a valve is configured to direct, at the appropriate time, some of the compressed air from the compressor, back to the air inlet of the compressor. However, such a valve also has disadvantages. For instance, the use of such a valve effectively results in the same content of air being circulated and re-circulated through the compressor and blow-off valve, with the result that the air becomes heated, both by the compressor and the surrounding engine. This increased temperature of the air has detrimental effects on the performance of the engine.
It is an object of the invention to overcome or ameliorate at least one of the disadvantages of the prior art or to provide a useful alternative.
According to a first aspect of the invention, there is provided, in an internal combustion engine having a compressor for supercharging the engine, the compressor including a compressor inlet for receiving gas to the compressor and a compressor outlet for expelling compressed gas from the compressor, a method of handling expelled compressed gas, the method including the steps of:
exhausting a first portion of the compressed gas to atmosphere after setting variable first control means configured for varying the volume flow rate of exhaustion of the first portion; and
directing a second portion of the compressed gas to the compressor inlet.
Preferably, the step of directing the second portion is carried out after setting variable second control means configured for varying the volume flow rate of the second portion. The setting of the first control means is preferably interdependent on the setting of the second control means.
In a preferred embodiment, the engine includes gas piping connected in fluid-flow communication with the compressor outlet and an engine throttle in the piping spaced from the compressor outlet, the steps of exhausting a first portion and directing a second portion being carried out on the expelled compressed gas between the compressor outlet and the throttle.
According to a second aspect of the invention, there is provided a blow-off valve apparatus for use in an internal combustion engine having a compressor for supercharging the engine, the compressor including a compressor inlet for receiving gas to the compressor and a compressor outlet for expelling compressed gas from the compressor, the apparatus including:
an apparatus inlet configured for connection in fluid-flow communication to the compressor outlet for receiving expelled compressed gas from the compressor;
a first apparatus outlet configured to exhaust, to atmosphere, a first portion of the gas received by the apparatus inlet;
variable first control means configured for varying the volume flow rate of exhaustion of the first portion through the first apparatus outlet; and
a second apparatus outlet configured for being connected in fluid-flow communication to the compressor inlet and for directing a second portion of the gas received by the apparatus inlet, to enable the second portion to be returned to the compressor inlet when the second apparatus outlet is connected to the compressor inlet.
Preferably, the apparatus includes variable second control means configured for varying the volume flow rate of the second portion through the second apparatus outlet.
The first control means is preferably a first closure configured for variably closing the first apparatus outlet and the second control means is preferably a second closure configured for variably closing the second apparatus outlet. Preferably the first and second closures are inter-dependently operable and they preferably constitute part of a single closure element.
In a preferred embodiment, the apparatus includes a housing having a cylindrical portion, the first and second apparatus outlets opening through the cylindrical portion. The single element is preferably constituted by a cylindrical first sleeve disposed substantially coaxially within the cylindrical portion, the first sleeve being configured to variably close the first apparatus outlet and the second apparatus outlet.
Preferably the first sleeve defines a pair of apertures and is rotatable relative to the housing for bringing at least one of the apertures into and out of alignment with the first apparatus outlet and at least the other of the apertures into, and out of, alignment with the second apparatus outlet. In a preferred embodiment, the apertures are larger than the apparatus outlets, the sleeve being configured for respectively variably closing each apparatus outlet while not restricting the other apparatus outlet.
The apparatus preferably includes an actuator connected to the first sleeve for rotating the first sleeve relative to the housing. Preferably the actuator is disposed outside the housing.
In a preferred embodiment, the apparatus includes a shut-off means for substantially preventing the expelled compressed gas from being received to the apparatus via the apparatus inlet. The shut-off means is preferably a barrier for closing the first and apparatus outlets. Preferably, the barrier is a second sleeve disposed coaxially within the cylindrical portion, and more preferably coaxially within the first sleeve. Preferably the second sleeve is axially movable relative to the cylindrical portion of the housing for closing the apparatus inlet and apparatus outlet.
The apparatus preferably includes a spring means for urging the second sleeve to a closure position to close the apparatus inlet and apparatus outlet, and opening means for moving the second sleeve from the closure position. Preferably the opening means includes a vacuum connector configured to enable a partial vacuum pressure to be applied thereto to urge the second sleeve, from the closure position against the urging of the spring means.
According to a third aspect of the invention, there is provided a system for use in a internal combustion engine, the system including:
a compressor for supercharging the engine, the compressor having a compressor inlet for receiving gas to the compressor and a compressor outlet for expelling compressed gas from the compressor; and
an apparatus according to the second aspect of the invention wherein the apparatus inlet is connected in fluid-flow communication to the compressor outlet and the second apparatus outlet is connected in fluid-flow communication to the compressor inlet.
According to a fourth aspect of the invention there is provided an internal combustion engine including:
at least one combustion cylinder having a cylinder fuel/air inlet and a cylinder exhaust outlet;
a compressor for supercharging the engine, the compressor having a compressor inlet for receiving gas to the compressor and a compressor outlet for expelling compressed gas from the compressor,
piping which connects, and which establishes fluid-flow communication between the compressor outlet and the cylinder fuel/air inlet; and
an apparatus according to the second aspect of the invention wherein the apparatus inlet is connected in fluid-flow communication to the piping and the first apparatus outlet is connected in fluid-flow communication to the compressor inlet.
Preferably, the compressor is a turbo-charging compressor being connected to a turbine, and the cylinder exhaust outlet is connected in fluid-flow communication to the turbine to enable exhaust gases exiting the at least one cylinder to drive the turbine in rotation.
In this specification, the term xe2x80x9cto atmospherexe2x80x9d and similar terminology where it appears, is to be understood to mean to the ambient surroundings.
It will be appreciated that the invention, at least in certain preferred embodiments, allows for the control of undesirable sound emitted by the engine due to air passing through the blow-off valve, and for keeping the air that is forced into the engine at a cooler temperature. Furthermore, in certain embodiments, by allowing for the fine-tuning of the proportion between the air diverted back to the compressor inlet and that exhausted to atmosphere, a desirable mixture between hot and cold air, and thus desirable overall temperature, can be achieved, and fuel consumption by the engine can be reduced.
Moreover, in certain embodiments, less decelerating force is applied to the supercharger so that, particularly where the supercharger is a turbocharger, its turbine/compressor assembly is able to continue rotating under its own inertia when the throttle is closed. This allows the lag time required to establish a desirable boost pressure, once the throttle has reopened, to be minimized.